1 files changed, 21 insertions, 4 deletions

diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 340b3f8b090d..f0561ee16b9c 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -58,7 +58,7 @@ void rcu_qs(void)
 		rcu_ctrlblk.donetail = rcu_ctrlblk.curtail;
 		raise_softirq_irqoff(RCU_SOFTIRQ);
 	}
-	WRITE_ONCE(rcu_ctrlblk.gp_seq, rcu_ctrlblk.gp_seq + 1);
+	WRITE_ONCE(rcu_ctrlblk.gp_seq, rcu_ctrlblk.gp_seq + 2);
 	local_irq_restore(flags);
 }
 
@@ -139,8 +139,10 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused
 /*
  * Wait for a grace period to elapse.  But it is illegal to invoke
  * synchronize_rcu() from within an RCU read-side critical section.
- * Therefore, any legal call to synchronize_rcu() is a quiescent
- * state, and so on a UP system, synchronize_rcu() need do nothing.
+ * Therefore, any legal call to synchronize_rcu() is a quiescent state,
+ * and so on a UP system, synchronize_rcu() need do nothing, other than
+ * let the polled APIs know that another grace period elapsed.
+ *
  * (But Lai Jiangshan points out the benefits of doing might_sleep()
  * to reduce latency.)
  *
@@ -152,6 +154,7 @@ void synchronize_rcu(void)
 			 lock_is_held(&rcu_lock_map) ||
 			 lock_is_held(&rcu_sched_lock_map),
 			 "Illegal synchronize_rcu() in RCU read-side critical section");
+	WRITE_ONCE(rcu_ctrlblk.gp_seq, rcu_ctrlblk.gp_seq + 2);
 }
 EXPORT_SYMBOL_GPL(synchronize_rcu);
 
@@ -213,10 +216,24 @@ EXPORT_SYMBOL_GPL(start_poll_synchronize_rcu);
  */
 bool poll_state_synchronize_rcu(unsigned long oldstate)
 {
-	return READ_ONCE(rcu_ctrlblk.gp_seq) != oldstate;
+	return oldstate == RCU_GET_STATE_COMPLETED || READ_ONCE(rcu_ctrlblk.gp_seq) != oldstate;
 }
 EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu);
 
+#ifdef CONFIG_KASAN_GENERIC
+void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
+{
+	if (head) {
+		void *ptr = (void *) head - (unsigned long) func;
+
+		kasan_record_aux_stack_noalloc(ptr);
+	}
+
+	__kvfree_call_rcu(head, func);
+}
+EXPORT_SYMBOL_GPL(kvfree_call_rcu);
+#endif
+
 void __init rcu_init(void)
 {
 	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);